1. Field of the Invention
The present invention relates to a door locking knob structure which is mainly used for locking a door of a vehicle to prevent it from being opened.
2. Description of the Relateed Art
One type of conventional door locking knob structure has heretofore been arranged such that a door of a vehicle is selectively locked and unlocked by changing the amount by which a projecting part of a knob main body projects from the door. In this type of door locking knob structure, the projecting part of the knob main body is provided with an enlarged portion at the distal end thereof, or provided with a recess near the distal end portion, thereby allowing the knob main body to be actuated easily. However, the projecting part of the knob main body, which projects from the door, preferably has a smooth structure in which no projection or recess is provided in order to prevent the projecting part from being accidentally moved to unlock the door.
To overcome this problem, an arrangement in which a locking knob is provided on the indoor-side surface of a door has been proposed (e.g., Japanese Utility Model Laid-Open No. 127262/1981). However, in this structure also, the locking knob projects to such an extent that it readily catches the occupant's finger, clothes or the like so as to be accidentally moved to an unlocked position. Therefore, it is not possible to reliably prevent undesirable unlocking of the door.
In order to solve these problems, the applicant of the present invention has already proposed a knob structure in which a recess is defined at the lower end portion of the knob so that an unlocking operation is allowed to be conducted only when the door is unlocked intentionally. (see Japanese Utility Model Application No. 17221/1985). In this knob structure, however, a button which is adapted to define a recess at the lower end portion of the knob is secured to the door, and there is therefore a gap between the button and the locking knob when the knob is in a locking state, which means that it is still impossible to reliably prevent undesirable or accidental unlocking of the door.